The Ultraviolet Bands of Beryllium Chloride

Abstract

A band system in the near ultraviolet region (3468-3700A) is obtained by using a beryllium arc in an atmosphere of chlorine. Four heads are found for each band, the $^{S}R_{21}$ heads being about one-third as intense as the other heads. The system is due to a $^{2}\ensuremath{\Pi}\ensuremath{-}^{2}\ensuremath{\Sigma}$ transition with the $^{2}\ensuremath{\Pi}$ state an intermediate one between case a and case b. A complete rotational analysis is impossible but from the spacing of the lines in certain branches, ${B}^{\ensuremath{'}}≌0.8$ and $\frac{A}{B}≌31$. The isotope effect for chlorine is observed in -1 and +1 sequences and the $^{S}R_{21}$ head of the (0,0) band. From the heats of dissociation, it appears that the electronic excitation is due to the $^{1}D\ensuremath{\rightarrow}^{1}P$ transition in the beryllium atom.